This invention relates to needles for circular knitting machines capable of manufacturing hosiery and like articles. More particularly, the invention relates to needles useful in a stitch or loop transfer operation for creating hosiery having decorative patterns of openings formed therein.
Circular knitting machines carry out knitting operations which form multiple strands of yarn into a tubular form. Such machines can form yarn into knitted fabrics useful for many different products, dependent on, for example, the circumference of the machine cylinder, the gauge and size of needles. One typical application is the production of hosiery, such as socks, hose and stockings. Such machines include a plurality of needles positioned in axial slots formed in an exterior surface of a rotatable needle cylinder. A plurality of sinkers are mounted between the needles to hold the knitted loops. A feeder mechanism delivers yam onto the passing needles in succession. The yarn forms loops over each needle in a controlled manner.
Patterns of open areas in circular knitted fabric formed by dropping stitches in a controlled manner. Heretofore, the formation of open-work pattern designs has been limited to relatively coarse gauge machines because of the difficulty in transferring a loop from one needle an adjacent needle to thus form the opening in a controlled, reliable manner on fine gauge hosiery machines.
In other applications, transfer of the stitch may be accomplished to prevent running or "laddering" of hosiery products.
In the particular embodiment shown in this application for purposes of illustration, the knitting machine is a circular knitting machine of the type used for knitting hosiery. In this type of machine, the garment, as knitted, is held under tension in the throat of the cylinder. The pattern may be controlled by any type of patterning device, such as known electronic, electro-mechanical or mechanical devices.
Any type of knitting machine may be modified according to the general principles of this application, provided the stitches are otherwise capable of being transferred from one needle to another.
Creation of patterns in knitted articles by transferring stitches from one needle to another is known in the prior art. In one prior art knitting machine, the knitting needles of the machine are separated by transfer members which reside in and move in the same vertical plane as the knitting needles and therefore separate the needles at all times. This limits the gauge of the fabrics which can be knitted with this type of machine since the diameter of the machine must accommodate both the knitting needles and the transfer members. For this reason, it has heretofore been impractical to knit fine hosiery with intricate, decorative patterns formed by transferring stitches.
Another prior art device uses a dial plate eccentric with respect to the needle cylinder and defines with the needle cylinder an enlarged loop transfer zone. The dial plate includes horizontally-disposed punches which facilitate transfer of loops from the certain needles of the needle cylinder onto adjacent needles.
A transfer stitch operation involves transferring a stitch from a selected needle to a following needle. As used herein, a selected needle is a needle from which the transfer stitch is removed, and a following needle is an adjacent needle to which the transfer stitch is placed. To perform the transfer stitch operation, the stitch on the selected needle is enlarged or widened. Once the stitch on the selected needle is sufficiently enlarged, the following needle is inserted through the enlarged stitch such that the stitch can then be secured around the following needle. Finally, the selected needle is removed from the enlarged stitch thereby causing the selected needle to release the stitch. As a result, the stitch is completely transferred from the selected needle to the following needle and a controlled perforation is formed in the hosiery article being created. A pattern of perforations can be formed in the hosiery article by selecting needles in accordance with a pre-determined set of instructions.
Prior art devices transfer the stitch from one needle to another needle by first removing the stitch from one needle and then placing it onto the adjacent needle. This practice increases the likelihood of missed transfers and other defects in the finished product.
Because the stitches on a selected needle must be enlarged before they are transferred to an adjacent needle, a considerable amount of tension is exerted on the yarn. As a result, it is quite possible that the yarn will break during the transfer stitch operation. A broken yarn, like a run, makes the article being formed unusable. There exists a need for a needle that minimizes the tension on the yarn during the transfer stitch operation necessary to form decorative open-work in hosiery and other knitted products.
Another impediment to performing the transfer stitch operation is the limited space between and around needles. This problem is also accentuated by the presence of the sinkers between the needles which affect the orientation and size of the opening created when the stitches are enlarged. In addition to the need to minimize the tension on the yarn, the lack of space available between and around the needles greatly reduces the extent to which the stitches can be enlarged. As a result of these limitations to enlarging a selected stitch, adjacent needles entering an enlarged stitch have little room for error lest the adjacent needle not enter the enlarged stitch. This results in the stitch being dropped and a run being formed in the hosiery article being created.